Driving stakes or posts into the ground is required in many circumstances related to the building of foundations, fences, and other applications. The physical act of driving such stakes or posts is typically labor intensive and performed manually by a worker using a hammer or maul. In many circumstances, the numbers of stakes or posts that must be driven into the ground are such that manual placement of the stakes or posts is cost prohibitive and a mechanical means of performing the job is necessary to speed the process. In addition, the work site in which the stakes or posts must be driven may be remote or may not have an adequate power supply, thus the mechanical stake/post driver must be relatively lightweight and self-powered. In response to these concerns, others have disclosed mechanical stake/post drivers.
U.S. Pat. No. 6,347,672 discloses a hammer element configured to strike a stake or post. The hammer element is coupled to a handheld jackhammer via a spindle. The hammer element is housed within a guide assembly that comprises a lower portion to receive the stake/post and an upper portion to receive the spindle.
U.S. Pat. No. 5,806,608 discloses an air-driven post driver that includes a hammer assembly and post receiving assembly. The hammer assembly includes an air-driven piston hammer disposed within a cylinder bore of a cylinder body having an upward thrusting air passageway, which includes a radially oriented upward intake passageway and a longitudinally oriented upward discharge passageway, and a downward thrusting air passageway, which includes a radially oriented downward intake passageway and a longitudinally oriented. downward discharge passageway having a threaded downward discharge port.
U.S. Pat. No. 5,667,021 discloses a stake driver including a frame for supporting a hammer and a stake under the hammer. The hammer is secured upon movable mounts and is raised via a hoist and repeatedly dropped to effect the driving of the stake.
U.S. Pat. No. 5,494,117 discloses a metal fence post driving apparatus formed by a platform rearwardly supported by the three point hitch of a conventional tractor and having a fluid pressure generating unit on the platform driven by the tractor power takeoff. A mast having a top end portion rotatable about its vertical axis pivotally supports a boom intermediate its ends for horizontal and vertical pivoting movement of its respective end portions by a first fluid pressure operated cylinder. A second fluid pressure cylinder pays out and retracts one end portion of the wire line of a block and tackle unit for elevating and lowering a fluid pressure operated reciprocating unit axially disposed on a post top to be driven into the ground.
U.S. Pat. No. 5,107,935 discloses an accessory for ajackhammer comprising a clamping means for gripping the upper end of the stake so that the user can controllably drive the stake into the ground. The accessory includes a stake receiver that has a channel into which the end portion of the stake is inserted and further includes a jaw and clamping means for forcibly retaining the jaw against the inserted stake. The channel includes guide ways that permit it to be used interchangeably with the more common sizes and shapes of stakes.
U.S. Pat. No. 5,088,567 discloses a device having a plurality of guides and a striking mass movable by a hydraulic cylinder. The hydraulic cylinder is arranged with its longitudinal axis outside the path of the center of gravity of the striking mass. The striking mass can comprise a first elastomeric and/or plastic component and a second heavy metal component. Three guides, which can be parallel to the movement path of the center of gravity, are provided for guidance of the striking mass, the striking mass is preferably constructed to be guided at its respective areas.
U.S. Pat. No. 5,819,857 discloses a portable power driven post driver having an inner hollow cylinder open at its upper end and adapted to receive a post through a locking mechanism located at its lower end. The inner cylinder is located within an outer surface of the outer cylinder; the longitudinal axes of the two fluid powered cylinders being in alignment. A common piston rod extends between the two pistons and is attached by a fastening member to the inner cylinder, the fastening member extending through a slot in the outer cylinder. A valve receives compressed fluid, such as compressed air, and cyclically and alternately directs the compressed fluid to the two fluid powered cylinders to alternately raise the outer cylinder above the inner cylinder and to drive the upper cylinder downwardly into post driving contact with the upper end of a post held by the inner cylinder.
U.S. Pat. No. 4,665,994 discloses a portable hand held post driver which is fully operable by a single worker and which uses a fluid powered cylinder to drive posts into the ground. The cylinder raises a balanced driving weight and forces the weight down onto the post. The cylinder is reversed automatically at both the top and bottom of its stroke to automatically repeat the driving strokes so long as the operator holds a hand lever. The post is clamped to the frame of the implement by a clamp having an overcenter control linkage. Before the implement can be operated, a safety-linking pin must be intentionally released by operating a safety lever.
The common feature among all of these prior art devices is that each apparatus employs a striking mass to hammer the stake or post into the ground. However, in the area of pile driving, wherein the members being driven into the ground are much larger and requires significantly more energy, it has been found that when a pile is subjected to intense linear vibration along the axis of the pile, and when the weight of the vibratory driving apparatus is added to the weight of the pile, the rate of penetration is more frequently found to be considerably faster than would be obtained using a hammer-type apparatus.
Furthermore, by employing vibratory forces rather than a hammer-type force, the same hand-held tool used to drive the stake or post into the ground could be used to remove the stake or post after it has been set in place. Hammer-type stake/post drivers are incapable of removing a stake or post from the ground.
U.S. Pat. No. 5,725,329 discloses a linear-type pile driver that is suspended above a pile via a crane. The driver comprises a lifting shaft isolated from but slideably mounted within a piston assembly which is attached to a frame assembly, a cylinder assembly attached a reaction mass, the piston assembly being vibratorily positioned within the cylinder assembly and vibratorily driven by hydraulic fluid at a selectable frequency thereby vibrating the piston/frame assembly.
U.S. Pat. No. 4,819,740 discloses a rotational-type pile driver that is also suspended above a pile via a crane. The vibratory pile driver includes, among other elements, a pair of eccentric weights mounted on shafts for rotation about an axis transversely of the clamped piling for imparting vibratory forces to the piling as the eccentrics are driven in rotation.
These examples of pile drivers, however, are designed for driving and extracting piles, which are typically large timbers or pipes, and cannot be employed for the much smaller scale operation of driving stakes or posts. Thus, it is desirable to have a simple, lightweight, vibratory stake/post driving apparatus that could be used by an individual to efficiently set stakes or posts.